yes, Im worried about this too. And some fans dont seem to notice this at all.

Not all the original cast should be brought back. 4 x-men would be fine for me. more Magneto. But 6 would be too much already.

Yes four or five seems like enough. Bring back maybe two or three character that were there in the comics as a homage (Hugh, Halle, Daniel, Ian or Ellen) and the others should be those that serve the adapted storyline. (possibly patrick, famke, rebecca)